Re: [myhdl-list] Restrictions for conversion

[Christopher F. <chr...@gm...>]

You are correct, this currently is a limitation.  Adding support for this
is part on the MEP we recently created.

Regard,
Chris

** sent from mobile device **
On Dec 23, 2011 6:37 AM, "Oscar Diaz" <osc...@gm...> wrote:

> Hi
>
> I was doing some experiments with the conversion function, and I found
> a problem I'd like to discuss regarding access to members of data
> structures inside generators. Suppose you have a dict with some
> constants you need for the calculations:
>
> constants_list = {"myconst": 10}
> def trans_block(clk, din, dout, const_list):
>    @always(clk.posedge)
>    def proc():
>        dout.next = din + const_list["addconst"]
>    return instances()
>
> conversion fails with:
> myhdl.ConversionError: in file simpletest.py, line 22:
>    Object type is not supported in this context: const_list, <type 'dict'>
>
> Same occur if you have a list:
> myhdl.ConversionError: in file simpletest.py, line 22:
>    Object type is not supported in this context: const_list, <type 'list'>
>
> Or, even if you use an object with members accessed as attributes, like
> this:
>        dout.next = din + const_list.addconst
> conversion fails with:
> myhdl.ConversionError: in file simpletest.py, line 29:
>    Unsupported attribute: addconst
>
> A workaround is to access data outside the generator, with another
> variable name:
>
> constants_list = {"myconst": 10}
> def trans_block(clk, din, dout, const_list):
>    addconst = const_list["addconst"]
>    @always(clk.posedge)
>    def proc():
>        dout.next = din + addconst
>    return instances()
>
> However, it's kind of annoying to do that when you have a lot of
> variables to access. Something similar occurs when you access signals.
>
> What are your thoughts? Is it good to allow access data members
> whatever way you want or is better to have a fixed coding style? By
> the way, I think these kind of details should be explained in the
> conversion documentation.
>
> Best regards
>
> --
> Oscar Díaz
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